Heretofore, in this field, the manipulation, visualization and fabrication of useful nanoscale devices has proved difficult. The capability to observe and manipulate material simultaneously at the nanoscale level is predicted to be invaluable in the design of nano-fabrication devices. Experimental manipulation and real time observation in conjunction with a nanoscale size could be vital in determining not only beginning and end products but also intermediates in the process of polymerization and polymer crystallization, leading to supermolecular architecture via material synthesis.
Several approaches have been studies for micro and nanoscale manufacturing. Among the tools being used in imaging, atomic force microscopy (AFM) is capable of observing molecular structure of a variety of materials down to the sub-nano level resolution on a consistent basis; however, real time imaging is virtually impossible since a relatively large period of time must be used in the actual scanning to obtain the image. In spite of this limitation, it has been possible to conduct experimentation on physical phenomena, such as melting and re-crystallization of polymeric specimens, with moderate modifications to the device itself (3, 4).
One technique for micromanipulation is described in U.S. Pat. No. 6,569,382, issued to Edman, et al., which describes a method and apparatus for the electronic, homogeneous assembly and fabrication of microscale devices, including micron, sub-micron and nanoscale devices. Electronic transport of movable component devices is described using a fluidic medium to effect transport to a desired target location on a substrate or motherboard. Forces disclosed include electrophoretic force, electro-osmotic force, electrostatic force and/or dielectrophoretic force. For example, free field electro-osmotic forces are used singly or in combination, as well as in conjunction with yet other forces, such as fluidic forces, mechanical forces or thermal convective forces to move molecules. Transport may be effected through the use of driving electrodes so as to transport the component device to yet other connection electrodes. In certain embodiments, the connection electrodes may also be used with driving electrodes to transport electronically the component device to the connection electrodes.
Another method of fabrication is disclosed in U.S. Pat. No. 6,508,979, issued to Requicha, et al., in which a method for fabricating or prototyping a nanoscale object is disclosed. The method includes defining a sequence of nanolayers that represent the nanoscale object, constructing a current nanolayer on a first surface and depositing a sacrificial layer to cover the first surface but not the nanolayer. The nanolayer represents a slice of the nanoscale object. The nanolayer and the sacrificial layer provide a second surface on which a next nanolayer is constructed. The construction and deposition steps are repeated if the next nanolayer is not the last nanolayer. As with other methods of fabrication, the method also includes removing sacrificial layers to produce the nanoscale objects.
Yet another method is disclosed in U.S. Pat. No. 6,287,765, issued to Cubicciotti, in which methods are disclosed for detecting and identifying single molecules. In this method, multimolecular devices and drug delivery systems are prepared from synthetic heteropolymers, heteropolymeric discrete structures, multivalent heteropolymeric hybrid structures, aptameric multimolecular devices, multivalent imprints, tethered specific recognition devices, paired specific recognition devices, nonaptameric multimolecular devices and immobilized multimolecular structures.
Advances in TEM have allowed for real-time observation of high-temperature nanofiber formation (Helveg, et al., Atomic-Scale Imaging of Carbon Nano-fibre Growth, Nature, 426-429, 29 Jan. 2004). Helveg, et al., observed carbon-fiber formation at 500° C. as the fiber formed from hydrocarbon vapor behind a metal-catalyst. The state (structure or shape) of the catalyst particle during the growth process, however, remains unknown.